Cyclone



F. J.' FONTEIN Oct. 30, 1951 CYCLONE Filed Dec.

Patented Oct. 30', 1951 v CYCLONE Freerk Jan Fontein, Heerlen.Netherlands, as-

limor to De Directie van de Staatsmiinen in Limburg, Heerlen,Netherlands Application December 9, 1946. Serial No. 715,029

6 Claims.

Heretofore, cyclones have been principally used in the separation ofsolid particles from gases. or to concentrate or thicken suspensions ofsolid particles in liquids. In the copending application of Driessen etal., Serial No. 664,320, filed April 23, 1946, Patent No. 2,543,689,issued February 2'7, 1951, there is disclosed a process for separatingsolid particles of difierent grain size and diflerent specific gravityusing a cyclone, the process involving the mixing of the particles to beseparated with a liquid carrier and with relatively fine particles of aspecific gravity higher than the specific gravity of separation. I havefound that cyclones having the best separating effect in the separationof solid material from gases, and the best thickener efiect in the caseof suspensions of solid particles in liquids, have the lowest separationefi'ect in the case of the separation of particles of difierent grainsize and specific gravity in accordance with the Driessen et a1.process. This type of cyclone comprises essentially a shell in the formof an elongated frustum of a relatively steep cone.

The object of the present invention is to provide a cyclone with animproved form of vortex chamber which greatly raises the eificiency ofthe separating action in the case of particles of different grain sizeand specific gravity. To this end, the vortex chamber is made ofgenerally conical form with the inner surface thereof in axial sectiondefining an included angle which progressively increases toward theapex, providing a concave internal longitudinal contour. Theprogressively increasing angle may be defined by successive conicalfrusta of increasing flatness toward the apex, or the inner surface ofthe vortex chamber may be smoothly curved, as the sides of a bowl,adjacent the apex opening. Obviously the inner surface of the cyclonegenerally will define the outer envelope of the bod or mass rotatingwithin the cyclone.

Illustrative embodiments of the invention are shown in the accompanyingdrawing wherein:

Figure 1 is an axial section of a cyclone whose shell comprises a seriesof conical frusta,

Figure 2 is a partial section like that of Figure 1 showing theattainment of concavity curvilinearly instead of by broken straightlines as in Figure 1, and More 3 is a view like that of Figure 2 showina modification.

Referring to Figure 1, the cyclone shell is of generally conical formand comprises a cylindrical portion I surmounting a series of conicalfrusta 6, l and I. The cylindrical portion I is provided with a cover 8having an axial discharge opening in. Reference numera1 ll designates afeed pipe disposed tangentially to section 6 and debouching into theinterior thereof through an opening I2.

Section 6 is a frustum of a cone whose apex angle is 20. Section 1 hasan angularity of and section 8 an angularity of and defines an apexopening l3 which is rimmed outwardly by a discharge nozzle H. Theterminal section 8 may have an angularity anywhere from 60 to 90 orover. As for further characteristics, section 6 may have a diameter of60 mm., base opening III a diameter of 18 mm., with inlet opening I 2equivalent to 18 mm. in diameter. Section 6 may have a bottom diameterof 40 mm. and an altitude of 118 mm.; section 1 may have a bottomdiameterof 25 mm. and an altitude of 19 mm.; and section 8 may have anapex opening 7 mm. in diameter and an altitude of 9 mm. These data aregiven as illustrative of a preferred form of cyclone under theinvention.

In the practice, for example, of the aforementioned process of theDriessen et al. patent, it is desirable that any necessary addition ofrelatively fine particles be kept at a minimum. In this respect,comparison was made between a cyclone in accordance with the presentinvention, dimensioned as above, and a normal cyclone in which thevortex chamber was conical with an angularity throughout of 20, apexopening 7 mm. in diameter, base opening 18 mm. in diameter, inletopening equivalent to 18 mm. in diameter, and maximum base diameter 60mm.

The suspension was fed at the same velocity in both instances but lessand less of the relatively fine particles was added so that the specificgravity of the suspension was progressively lowered.

In the case of the conventional cyclone, when the specific gravity waslowered to 1.07, all separating efiect disappeared. However, with thenew cyclone and the specific gravity of the input at 1.07, there wasstill a very sharp specific gravity of separation at 1.42.

In the above tests the particles to be separated were intermixed coaland shale. With the specific gravity of the suspension greatly reducedby diminishing the amount of relatively fine particles added to thesuspension, the conventional cyclone was inoperative whereas the newcyclone maintained an effective specific gravity of separation. Sincethe added relatively fine particles have to be recovered, it is obviousthat the smaller the amount necessary to be added, the better, andconsequently the new cyclone is of outstanding advantage in the practiceof the said Driessen et a1. process.

In Figure 2 the cyclone is the same as that of Figure 1 except at itsapex end which is longitudinally curvilinear. Section 1a between theimaginary lines a: and 11 corresponds in position and axial extent withsection I of Figure 1 and section 8a with section 8. The angles, or meanangles, of section la and 8a correspond with those of sections 1 and 8,respectively. Operational results are the same, the diiIerence beingthat the conical frusta l and 8 are advantageous from a constructionalviewpoint, being more readily formed than the curved section.

The apex end of the cyclone shell may be longitudinally convexed to thedischarge opening with further improved results. In Figure 3, the bodyof the cyclone is like that of Figure 2 except that at the apex end, theconcavity merges into an internally convexly curved funnel-like spout l5which defines the discharge opening. In the illustrated form, anyelement of the shell has at its apex end a concavity which mergessmoothly into a terminal convexity. This same form of spout could beprovided with the shell of Figure 1.

Variations in form and proportions, beyond those disclosed, arecontemplated under the claims which follow.

I claim:

1. The continuous process of separating into two fractions a liquidsuspension having particles diverse both as to grain size and specificgravity whereby all particles of specific gravity less than apredetermined specific gravity of separation pass into one fractionwhile a second fraction contains particles of a specific gravity greaterthan the specific gravity of separation, which comprises establishingand maintaining a rotating body of such suspension in a confinedgenerally conical space having axial discharge outlets at its ends fromwhence one fraction is continuously discharged from one such end whileanother fraction is continuously discharged from the other, continuouslysupplying such suspension tangentially to the rotating body in theregion of the base of the conical space, and selectively controlling thespecific gravity of separation by augmenting the suspension in the bodywith a solid material divided significantly finer than the smallestparticles to be fractionated but having itself a specific gravity abovethe specific gravity of separation and in quantity suflicient toestablish and maintain a barrier made up of mobilized solids disposed inthe cyclone at its apex that is permeable by the particles of specificgravity greater than the specific gravity of separation but impermeableto the particles of specific gravity smaller than the specific gravityof separation, and maintaining the major portion of the length of theouter envelope of the rotating body within an included angle of theorder of 20 and progressively increasing the included angle of theenvelope from such included angle to the apex of the space to therebyminimize the quantity or augmenting material required.

2. A process of the character described in claim 1 wherein the outerenvelope is a series of frustra.

3. A process of the character described in claim 1 wherein the portionof the outer envelope which has a progressively increasing includedangle is curved lengthwise of the generally conical space.

4. A process of the character described in claim 1 wherein the portionof the outer envelope which has a progressively increasing includedangle has a length which is approximately onefourth that of the majorportion 01 the length.

5. A process of the character described in claim 1 wherein the initialincrease of the included angle is of the order of 40.

6. A process of the character described in claim 1 wherein the includedangle adjacent the apex is greater than 60.

FREERK JAN FONTEHN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 446,053 Bittinger Feb. 10, 1891709,956 Bailey Sept. 30. 1902 938,702 Porbeck Nov. 2, 1909 1,265,763Fender May 14, 1918 1,832,256 Stebbins Nov. 17, 1931 2,377,524 Sampsonet al June 5, 1945 2,471,326 Hoyt, Sr May 24, 1949 FOREIGN PATENTSNumber Country Date 378,696 Italy Sept. 22, 1938

